The present invention relates to a self-emission panel, and a method of manufacturing the same.
The present application claims priority from Japanese Patent Application No. 2005-208822, the disclosure of which is incorporated herein by reference.
Self-emission panels, typified by organic electroluminescence (EL) panels, are now under intensive research and development in expectation of various applications. The possible applications include the display units of cellular phones, low-profile television sets, information terminals, and the like, as well as car-mounted function displays including such instrument panels as a speed indicator, function display units of electric appliances, film-like display units, outdoor signboards, and lightings.
These self-emission panels are each formed by arranging one or a plurality of self-emission devices on a substrate. Among examples of the self-emission devices are such light-emitting devices as an LED (Light-Emitting Diode) and an FED (Field Emission Display), aside from organic EL devices.
These self-emission devices have the structure that a first conductive layer is formed on a substrate directly or via other layers, a deposition layer including a luminescent layer is laminated on the first conductive layer, and a second conductive layer is formed on the deposition layer. When a voltage is applied to between the first conductive layer and the second conductive layer, electrons are injected from a cathode-side, or either one of the first and second conductive layers, and holes are injected from an anode-side, or the other of the first and second conductive layers. Then, in the luminescent layer or the like, the electrons and holes are recombined for light emission.
With such self-emission devices, the surface flatness of the first conductive layer has a significant impact on the performance of the devices and by extension the self-emission panels since at least the deposition layer including the luminescent layer is formed on the first conductive layer. Japanese Patent Application Laid-Open Publication No. Hei 9-245965 has proposed an organic EL device which comprises an anode, at least one organic layer including an organic luminescent layer, and a cathode. In this organic EL device, at least the surface of the anode in contact with the organic layer is polished so that it has a surface roughness of 50 angstroms or less in maximum height (Rmax: JIS B0601).
As discussed in the foregoing publication, self-emission panels can cause performance deteriorations including an emission failure. Among possible causes is the occurrence of a short circuit between the first conductive layer and the second conductive layer. Possible causes of this short circuit, in turn, include foreign substances such as dust adhering to the surface of the first conductive layer (for example, anode) that is formed on the substrate. To avoid this, as in the foregoing publication, surface polishing is performed to flatten the surface after the formation of the first conductive layer (anode). Nevertheless, even after the polishing of the first conductive layer (anode), dust and other foreign substances can adhere to the top of the first conductive layer (anode) in the process of making openings in an insulating film or the like, going through a deposition preprocessing step such as UV, ozone, or plasma irradiation and heating, and finally performing the step of depositing the deposition layer. An example will be given below.
As shown in FIG. 1A, a first conductive layer 3j (anode) is formed on a substrate 2j, and a sectioning layer 4j for sectioning emission areas A1 is formed thereon. This sectioning layer 4j sections openings S for a deposition layer to be laminated in. When patterning this sectioning layer 4j, foreign substances such as dust particles 21 and 22, and resists, oxidized films, and other coatings 23 can adhere to the exposed surfaces of the first conductive layer 3j. As shown in FIG. 1B, structures such as barrier portions 5j are sometimes formed, on the sectioning layer 4j. Since it is impossible to perform the foregoing polishing after the formation of the sectioning layer 4j, the barrier portions 5j, and other structures, there has been the problem that foreign substances described above cannot be removed to avoid emission failures.